The cap section of an aluminum alloy wheel is a joint area of a casting surface and a machining surface and thus has a ring of burrs. The traditional burr removing method is relatively low in positioning precision and poor in consistency of removal of burrs at the cap section edge, and has a phenomenon of non-uniformity, i.e., the removal quantity may be too large on one side of the cap section edge and too small on the other side. Due to low precision when the burrs are removed, chamfers at the cap section edge are not uniform, the thickness of a film after coating is also not uniform, the film at large chamfers is too thick, whereas the film at small chamfers is insufficient in thickness, thus finally causing corrosion, experimental failure and even customer complaint.